Question

The number of students weighing less than 30 kg in a section is ten. There are 15 students who weigh less than 35 kg, and 20 students who weigh less than 40 kg.
The frequency table for the given data is a follows: Weight Range Number of Students

$0<\text{Weight (kg)}<30$	$10$
$0<\text{Weight (kg)}<35$	$15$
$0<\text{Weight (kg)}<40$	$20$

Then there are
students who weigh more than or equal to 35 kg.

Answer 1

The statement "Number of students weighing less than $30$ kg is $10$" can be interpreted as follows:

Number of students in the range $0<\text{Weight (kg)}<30$ is $10.$

The frequency table for the given data is a follows: Weight Range Number of Students

$0<\text{Weight (kg)}<30$	$10$
$0<\text{Weight (kg)}<35$	$15$
$0<\text{Weight (kg)}<40$	$20$

Subtracting the number of students in the range $0<\text{Weight (kg)}<30$ from the range $0<\text{Weight (kg)}<35$ we get,

Number of students in the range $30\le \text{Weight (kg)}<35$ is $15-10=5.$

Similarly, subtracting the number of students in the range $0<\text{Weight (kg)}<35$ from the range $0<\text{Weight (kg)}<40$ we get,

Number of students in the range $35\le \text{Weight (kg)}<40$ is $20-15=5.$

The grouped frequency table is: Weight Range Number of Students

$0<\text{Weight (kg)}<30$	$10$
$30\le \text{Weight (kg)}<35$	$5$
$35\le \text{Weight (kg)}<40$	$5$

The number of students weighing more than or equal to $35$ kg is equivalent to the number of students in the interval $35\le \text{Weight (kg)}<40$, i.e., $5.$

$\therefore 5$ is the required answer.